1. Compound specific isotope analysis of organophosphorus pesticidesPolonca Trebše, Langping Wu, Jun Yao, Ning Zhang, Hans H. Richnow, 2014, original scientific article Found in: osebi Keywords: pesticidi, diklorvos, ometoat, dimetoat, CSIA Published: 16.06.2016; Views: 3724; Downloads: 16
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2. A nanomesh scaffold for supramolecular nanowire optoelectronic devicesLei Zhang, Egon Pavlica, Gvido Bratina, 2016, original scientific article Abstract: Supramolecular organic nanowires are ideal nanostructures for optoelectronics because they exhibit both efficient exciton generation as a result of their high absorption coefficient and remarkable light sensitivity due to the low number of grain boundaries and high surface-to-volume ratio. To harvest photocurrent directly from supramolecular nanowires it is necessary to wire them up with nanoelectrodes that possess different work functions. However, devising strategies that can connect multiple nanowires at the same time has been challenging. Here, we report a general approach to simultaneously integrate hundreds of supramolecular nanowires of N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) in a hexagonal nanomesh scaffold with asymmetric nanoelectrodes. Optimized PTCDI-C8 nanowire photovoltaic devices exhibit a signal-to-noise ratio approaching 107, a photoresponse time as fast as 10 ns and an external quantum efficiency >55%. This nanomesh scaffold can also be used to investigate the fundamental mechanism of photoelectrical conversion in other low-dimensional semiconducting nanostructures. Found in: osebi Keywords: fotodetektor, organski polprevodnik, fotoprevodnost, organski kristal, elektronske komponente, nanožice Published: 05.10.2016; Views: 4728; Downloads: 0
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3. Fast-Response Photonic Device Based on Organic-Crystal Heterojunctions Assembled into a Vertical-Yet-Open Asymmetric ArchitectureLei Zhang, Pavlica Egon, Zhong, Xiaolan, Liscio Fabiola, LI Songlin, Bratina Gvido, Orgiu Emanuele, Samori Paolo, 2017, original scientific article Found in: osebi Keywords: organski polprevodniki, merjenja časa preleta, organski fotodetektorji Published: 24.01.2017; Views: 3500; Downloads: 0
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4. Conclusively Addressing the CoPc Electronic Structure: A Joint Gas- Phase and Solid-State Photoemission and Absorption Spectroscopy StudyMarcello Coreno, Monica de Simone, Ieva Bidermane, Y. Sassatelli, R. Ovsyannikov, Erika Giangrisostomi, C. Grazioli, J. Lüder, Valeria Lanzillotto, I.E. Brumboiu, Teng Zhang, Barbara Ressel, Matija Stupar, Maddalena Pedio, Petra Rudolf, Barbara Brena, Carla Puglia, 2017, original scientific article Found in: osebi Keywords: Cobalt Phtalocyanine, photoemission spectroscopy, gas phase, solid state Published: 07.02.2018; Views: 3520; Downloads: 0
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5. Energy response of ISS-CREAM calorimeter with attenuation effectJ. P. Lundquist, H.G. Zhang, 2020, other component parts Abstract: The NASA mission, Cosmic Ray Energetic And Mass experiment for the International Space Station (ISS-CREAM) is to measure individual cosmic-ray particle energy spectra from protons to iron nuclei, with an energy range from ~1 TeV to the so-called "knee", near 1015eV. Energies of cosmic-ray particles are measured from electromagnetic showers induced by particles in the calorimeter.
As a pioneer mission, the balloon-borne CREAM instrument has successfully flown seven times over the Antarctica for a cumulative exposure of 191 days. The CREAM calorimeter has shown sufficient capability to measure energies of cosmic-ray particles by capturing the electromagnetic shower profile within the interested energy range. The ISS-CREAM calorimeter is expected to have a similar performance and, before it was launched, an engineering-unit calorimeter was shipped to CERN for a full beam test. The full performance test includes position, energy, and angle scans of electron and pion beams together with a high voltage scan for calibration and characterization.
In addition to the regular analysis for performance test, we also applied an additional step to generate the universal energy responses by correcting the attenuation effect in the calorimeter readout. The general energy responses could be obtained after shifting the incident beam positions to a reference position near the center of the calorimeter, which provided improved energy resolutions. The result of this analysis will be used to determine the incident energies of the cosmic-ray particles in the flight data. Found in: osebi Keywords: cosmic rays, high-energy, particle physics, detectors Published: 29.04.2020; Views: 2304; Downloads: 133
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6. Substantial brown carbon emissions from wintertime residential wood burning over FranceJean-Luc Jaffrezo, Valérie Gros, Griša Močnik, Gilles Levigoureux, Marta Dominik-Sègue, Eve Chrétien, Sabrina Pontet, Gregory Gille, Florie Chevrier, Véronique Jacob, Jean-Eudes Petit, Alexandre Albinet, Yunjiang Zhang, Olivier Favez, 2020, original scientific article Abstract: Brown carbon (BrC) is known to absorb light at subvisible wavelengths but its optical properties and sources are still poorly documented, leading to large uncertainties in climate studies. Here, we show its major wintertime contribution to total aerosol absorption at 370 nm (18–42%) at 9 different French sites. Moreover, an excellent correlation with levoglucosan (r2 = 0.9 and slope = 22.2 at 370 nm), suggesting important contribution of wood burning emissions to ambient BrC aerosols in France. At all sites, BrC peaks were mainly observed during late evening, linking to local intense residential wood burning during this time period. Furthermore, the geographic origin analysis also highlighted the high potential contribution of local and/or small-regional emissions to BrC. Focusing on the Paris region, twice higher BrC mass absorption efficiency value was obtained for less oxidized biomass burning organic aerosols (BBOA) compared to more oxidized BBOA (e.g., about 4.9 ± 0.2 vs. 2.0 ± 0.1 m2 g−1, respectively, at 370 nm). Finally, the BBOA direct radiative effect was found to be 40% higher when these two BBOA fractions are treated as light-absorbing species, compared to the non-absorbing BBOA scenario. Found in: osebi Keywords: Brown carbon, Multi sites, Residential wood burning, Mass absorption efficiency, France Published: 20.07.2020; Views: 2216; Downloads: 0
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7. Molecular and physical characteristics of aerosol at a remote free troposphere siteSimeon K. Schum, Bo Zhang, Katja Džepina, Paulo Fialho, Claudio Mazzoleni, Lynn R. Mazzoleni, 2018, original scientific article Abstract: Aerosol properties are transformed by atmospheric processes during long-range transport and play a key role in the Earth’s radiative balance. To understand the molecular and physical characteristics of free tropospheric aerosol, we studied samples collected at the Pico Mountain Observatory in the North Atlantic. The observatory is located in the marine free troposphere at 2225m above sea level, on Pico Island in the Azores archipelago. The site is ideal for the study of long-range-transported free tropospheric aerosol with minimal local influence. Three aerosol samples with elevated organic carbon concentrations were selected for detailed analysis. FLEXPART retroplumes indicated that two
of the samples were influenced by North American wildfire
emissions transported in the free troposphere and one by
North American outflow mainly transported within the marine
boundary layer. Ultrahigh-resolution Fourier transform
ion cyclotron resonance mass spectrometry was used to determine
the detailed molecular composition of the samples.
Thousands of molecular formulas were assigned to each of
the individual samples. On average ~60% of the molecular
formulas contained only carbon, hydrogen, and oxygen
atoms (CHO), ~ 30% contained nitrogen (CHNO), and
~ 10% contained sulfur (CHOS). The molecular formula
compositions of the two wildfire-influenced aerosol samples
transported mainly in the free troposphere had relatively low
average O=C ratios (0:48 ± 0:13 and 0:45 ± 0:11) despite the
7–10 days of transport time according to FLEXPART. In contrast,
the molecular composition of the North American outflow
transported mainly in the boundary layer had a higher
average O=C ratio (0:57 ± 0:17) with 3 days of transport time.
To better understand the difference between free tropospheric
transport and boundary layer transport, the meteorological
conditions along the FLEXPART simulated transport pathways
were extracted from the Global Forecast System analysis
for the model grids. We used the extracted meteorological
conditions and the observed molecular chemistry to predict
the relative-humidity-dependent glass transition temperatures
(Tg) of the aerosol components. Comparisons of the
Tg to the ambient temperature indicated that a majority of
the organic aerosol components transported in the free troposphere were more viscous and therefore less susceptible to
oxidation than the organic aerosol components transported
in the boundary layer. Although the number of observations
is limited, the results suggest that biomass burning organic
aerosol injected into the free troposphere is more persistent
than organic aerosol in the boundary layer having broader
implications for aerosol aging. Found in: osebi Keywords: secondary organic aerosols, brown carbon, particle dispersion model, ultrahigh-resolution FT-ICR MS, Pico Mountain Observatory Published: 10.04.2021; Views: 1437; Downloads: 0
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8. Ice cloud formation potential by free tropospheric particles from long-range transport over the Northern Atlantic OceanClaudio Mazzoleni, Katja Džepina, Kendra Wright, R. Chris Owen, Paulo Fialho, Lynn R. Mazzoleni, Swarup China, Peter A. Alpert, Bo Zhang, Simeon K. Schum, 2017, original scientific article Abstract: Long-range transported free tropospheric particles can play a significant role on heterogeneous ice nucleation. Using optical and electron microscopy we examine the physicochemical characteristics of ice nucleating particles (INPs). Particles were collected on substrates from the free troposphere at the remote Pico Mountain Observatory in the Azores Islands, after long-range transport and aging over the Atlantic Ocean. We investigate four specific events to study the ice formation potential by the collected particles with different ages and transport patterns. We use single-particle analysis, as well as bulk analysis to characterize particle populations. Both analyses show substantial differences in particle composition between samples from the four events; in addition, single-particle microscopy analysis indicates that most particles are coated
by organic material. The identified INPs contained mixtures of dust, aged sea salt and soot, and organic material acquired either at the source or during transport. The temperature and relative humidity (RH) at which ice formed, varied only by 5% between samples, despite differences in particle composition, sources, and transport patterns. We hypothesize that this small variation in the onset RH may be due to the coating material on the particles. This study underscores and motivates the need to further investigate how long-range transported and atmospherically aged free tropospheric particles impact ice cloud formation. Found in: osebi Keywords: atmospheric aerosols, ice nucleating particles, long-range transport, optical microscopy, electron microscopy, Pico Mountain Observatory Published: 11.04.2021; Views: 1492; Downloads: 122
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9. Morphology and mixing state of aged soot particles at a remote marine free troposphere siteSumit Kumar, Katja Džepina, Michael P. Dziobak, Paulo Fialho, Judith A. Perlinger, Swarup China, Barbara Scarnato, Robert C. Owen, Bo Zhang, MarianT. Ampadu, 2015, original scientific article Abstract: The radiative properties of soot particles depend on their morphology and mixing state, but their evolution during transport is still elusive. Here we report observations from an electron microscopy analysis of individual particles transported in the free troposphere over long distances to the remote Pico Mountain Observatory in the Azores in the North Atlantic. Approximately 70% of the soot particles were highly compact and of those 26% were thinly coated. Discrete dipole approximation simulations indicate that this compaction results in an increase in soot single scattering albedo by a factor of <= 2.17. The top of the atmosphere direct radiative forcing is typically smaller for highly compact than mass-equivalent lacy soot. The forcing estimated using Mie theory is within 12% of the forcing estimated using the discrete dipole approximation for a high surface albedo, implying that Mie calculations may provide a reasonable approximation for compact soot above remote marine clouds. Found in: osebi Keywords: atmospheric aerosol, soot, long-range transport, free troposphere, single scattering albedo Published: 11.04.2021; Views: 1391; Downloads: 0
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10. Molecular characterization of free tropospheric aerosol collected at the Pico Mountain ObservatoryJ. Hueber, Sumit Kumar, J. A. Perlinger, Katja Džepina, Claudio Mazzoleni, Paulo Fialho, Swarup China, Bo Zhang, R. Chris Owen, D. Helmig, 2015, original scientific article Abstract: Free tropospheric aerosol was sampled at the
Pico Mountain Observatory located at 2225 m above mean
sea level on Pico Island of the Azores archipelago in the
North Atlantic. The observatory is located ∼ 3900 km east
and downwind of North America, which enables studies
of free tropospheric air transported over long distances.
Aerosol samples collected on filters from June to October
2012 were analyzed to characterize organic carbon, elemental carbon, and inorganic ions. The average ambient concentration of aerosol was 0.9 ± 0.7 µg m−3
. On average, organic aerosol components represent the largest mass fraction of the total measured aerosol (60 ± 51 %), followed by
sulfate (23 ± 28 %), nitrate (13 ± 10 %), chloride (2 ± 3 %),
and elemental carbon (2 ± 2 %). Water-soluble organic matter (WSOM) extracted from two aerosol samples (9/24 and
9/25) collected consecutively during a pollution event were
analyzed using ultrahigh-resolution electrospray ionization
Fourier transform ion cyclotron resonance mass spectrometry. Approximately 4000 molecular formulas were assigned
to each of the mass spectra in the range of m/z 100–1000.
The majority of the assigned molecular formulas had unsaturated structures with CHO and CHNO elemental compositions. FLEXPART retroplume analyses showed the sampled
air masses were very aged (average plume age > 12 days).
These aged aerosol WSOM compounds had an average O /C
ratio of ∼ 0.45, which is relatively low compared to O /C
ratios of other aged aerosol. The increase in aerosol loading during the measurement period of 9/24 was linked to
biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in the WSOM
and with the morphology and mixing state of particles as
determined by scanning electron microscopy. The presence
of markers characteristic of aqueous-phase reactions of phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses of 9/25 were
more aged and influenced by marine emissions, as indicated
by the presence of organosulfates and other species characteristic of marine aerosol. The change in the air masses for
the two samples was corroborated by the changes in ethane,
propane, and ozone, morphology of particles, as well as by
the FLEXPART retroplume simulations. This paper presents
the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere
remote location and provides evidence of low oxygenation
after long-range transport. We hypothesize this is a result of
the selective removal of highly aged and polar species during long-range transport, because the aerosol underwent a
combination of atmospheric processes during transport facilitating aqueous-phase removal (e.g., clouds processing) and
fragmentation (e.g., photolysis) of components. Found in: osebi Keywords: organic aerosol, ultrahigh-resolution FT-ICR MS, electron microscopy, remote marine atmosphere, Pico Mountain Observatory Published: 11.04.2021; Views: 1419; Downloads: 0
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